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Biomedical subjects

Joseph Lau

Publications and source records attributed to Joseph Lau.

At least 19 recordsLinked to original sources
PubMed2006

Effects of omega-3 fatty acids on serum markers of cardiovascular disease risk: a systematic review.

Greater fish oil consumption has been associated with reduced CVD risk, although the mechanisms are unclear. Plant-source oil omega-3 fatty acids (ALA) have also been studied regarding their cardiovascular effect. We conducted a systematic review of randomized controlled trials that evaluated the effect of consumption of fish oil and ALA on commonly measured serum CVD risk factors, performing meta-analyses when appropriate. Combining 21 trials evaluating lipid outcomes, fish oil consumption resulted in a summary net change in triglycerides of -27 (95% CI -33, -20)mg/dL, in HDL cholesterol of +1.6 (95% CI +0.8, +2.3)mg/dL, and in LDL cholesterol of +6 (95% CI +3, +8)mg/dL. There was no effect of fish oil on total cholesterol. Across studies, higher fish oil dose and higher baseline levels were associated with greater reductions in serum triglycerides. Overall, the 27 fish oil trials evaluating Hgb A(1c) or FBS found small non-significant net increases compared to control oils. Five studies of ALA were inconsistent in their effects on lipids, Hgb A(1c) or FBS. Four studies investigating the effects of omega-3 fatty acids on hs-CRP were also inconsistent and non-significant. The evidence supports a dose-dependent beneficial effect of fish oil on serum triglycerides, particularly among people with more elevated levels. Fish oil consumption also modestly improves HDL cholesterol, increases LDL cholesterol levels, but does not appear to adversely affect glucose homeostasis. The evidence regarding the effects of omega-3 fatty acids on hs-CRP is inconclusive, as are data on ALA.

Biomarkers↗
PubMed2006

Differences in characteristics of nocturnal enuresis between children and adolescents: a critical appraisal from a large epidemiological study.

OBJECTIVE: To evaluate any differences in the characteristics of primary nocturnal enuresis (PNE) between younger enuretic children and adolescents. SUBJECTS AND METHODS: In all, 21 000 questionnaires designed to determine the presence or absence of bed-wetting, diurnal incontinence, frequency of wetting, systemic illness, and family history, were sent to children aged 5-19 years from 67 kindergartens, primary schools and secondary schools randomly selected by a computer from different areas in Hong Kong. In addition, questions were asked to evaluate when and how the parents became aware that bed-wetting is a significant medical problem deserving attention in children after the age of 5 years. RESULTS: Of the 21,000 questionnaires distributed, 16 512 (78.6%) were completed. Among the respondents, 512 children (302 boys, 210 girls) had PNE; of these, 106 (20.7%) also had daytime incontinence. There was a marked reduction in the overall prevalence of PNE with advancing age. At 5 years old, 16.1% of children had PNE (20.7% boys, 10.8% girls; at age 9 and 19 years, 3.14% and 2.2% of children had PNE, respectively. However, this reduction was significantly more apparent among those with mild enuretic symptoms (wet <3 nights/week) than in those with more frequent bed-wetting. Furthermore, younger enuretic children behaved very differently from adolescents and older patients. As age increased there was a significant tendency towards more severe enuretic symptoms. At age 5 years, 14.3% of enuretic children wet 7 nights/week, compared with 48.3% at age 19 years (P < 0.001). In addition, significantly more adolescent boys aged >10 years had daytime urinary incontinence than had enuretic children aged < or = 10 years (32% vs 14.6%, respectively, P < 0.001). Most (89%) parents only became aware that bed-wetting was a significant medical problem deserving attention through material in the mass media over the past 3-4 years. CONCLUSIONS: The present finding suggesting that PNE spontaneously resolves with increasing age probably applies only to those with mild enuretic symptoms. There are significant differences in characteristics between younger enuretic children and older subjects. As age increases there is an increasing proportion of enuretic patients with more severe bed-wetting. Enuretic children aged >10 years and adolescents have significantly more daytime urinary symptoms and incontinence. The previously reported low prevalence of PNE in Hong Kong was probably due to parental indifference to the problem.

Adolescent↗
PubMed2005

Local literature bias in genetic epidemiology: an empirical evaluation of the Chinese literature.

BACKGROUND: Postulated epidemiological associations are subject to several biases. We evaluated whether the Chinese literature on human genome epidemiology may offer insights on the operation of selective reporting and language biases. METHODS AND FINDINGS: We targeted 13 gene-disease associations, each already assessed by meta-analyses, including at least 15 non-Chinese studies. We searched the Chinese Journal Full-Text Database for additional Chinese studies on the same topics. We identified 161 Chinese studies on 12 of these gene-disease associations; only 20 were PubMed-indexed (seven English full-text). Many studies (14-35 per topic) were available for six topics, covering diseases common in China. With one exception, the first Chinese study appeared with a time lag (2-21 y) after the first non-Chinese study on the topic. Chinese studies showed significantly more prominent genetic effects than non-Chinese studies, and 48% were statistically significant per se, despite their smaller sample size (median sample size 146 versus 268, p < 0.001). The largest genetic effects were often seen in PubMed-indexed Chinese studies (65% statistically significant per se). Non-Chinese studies of Asian-descent populations (27% significant per se) also tended to show somewhat more prominent genetic effects than studies of non-Asian descent (17% significant per se). CONCLUSION: Our data provide evidence for the interplay of selective reporting and language biases in human genome epidemiology. These biases may not be limited to the Chinese literature and point to the need for a global, transparent, comprehensive outlook in molecular population genetics and epidemiologic studies in general.

Asian People↗
PubMed2005

Effects of omega-3 fatty acids on coronary restenosis, intima-media thickness, and exercise tolerance: a systematic review.

Greater omega-3 fatty acid consumption is associated with reduced cardiovascular disease risk. Though the mechanisms of their effect are unclear, they may involve lesion formation and heart function. We conducted a systematic review of the clinical literature on the effect of omega-3 fatty acids on measures of vascular structure and function. We included studies that assessed fish and plant sources of omega-3 fatty acids on coronary artery restenosis after angioplasty, carotid IMT, and exercise capacity. Compared to placebo, the summary risk ratio of coronary artery restenosis with fish oil is 0.87 (95% CI 0.73, 1.05) across 12 randomized controlled trials. Two prospective studies reported increased carotid IMT, whereas two cross-sectional studies reported a reduction of IMT, with fish, fish oil or ALA consumption. Three randomized trials and three uncontrolled studies reported small non-significant improvements in exercise capacity with fish oil. Overall, little or no effect of fish oil was found for a variety of markers of cardiovascular disease risk. There are insufficient studies to draw conclusions about the effect of ALA. The dearth of long term data on fish consumption or omega-3 fatty acid supplementation on measures of cardiovascular disease risk severely limits our ability to draw definitive conclusions at this time.

Carotid Arteries↗
PubMed2005

Challenges in systematic reviews of diagnostic technologies.

Diagnostic tests are critical components of effective health care. They help determine treatments that are most beneficial for a given patient. Their assessment is a complex process that includes such challenges as a dearth of studies that evaluate clinical outcomes and lack of data on use of the test in realistic clinical settings. The methodologic quality of studies of diagnostic tests also lags behind the quality of studies of therapeutic interventions. Statistical methods to combine diagnostic accuracy data are more complex and not as well developed, leading to difficulties in the interpretation of results. The Agency for Healthcare Research and Quality Technology Assessment Program has adopted a 6-level framework for evaluating diagnostic technologies. The model emphasizes the need for systematic reviews of diagnostic test studies to go beyond the assessment of technical feasibility and accuracy to examine the impact of the test on health outcomes. In this paper, we use examples from 3 Evidence-based Practice Center reports to illustrate 3 challenges reviewers may face when reviewing diagnostic test literature: finding relevant studies, assessing methodologic quality of diagnostic accuracy studies, and synthesizing studies that evaluate tests in different patient populations or use different outcomes.

Diagnostic Techniques and Procedures↗
PubMed2005

Effects of fish oil supplementation on kidney transplantation: a systematic review and meta-analysis of randomized, controlled trials.

The objective of this study was to assess the effects of omega-3 fatty acid supplementation on various kidney transplant-related outcomes. A systematic review and meta-analysis was performed of published randomized, controlled trials (RCT). There were 16 kidney transplant RCT with a total of 812 patients. All trials evaluated fish oil with dosages that ranged from 1.2 to 5.4 g/d. No consistent benefits were observed for any outcome with the exception of a modest benefit on triglycerides. A meta-analysis of rejection episodes found no significant benefit on either early (<6 mo posttransplantation) or late episodes. The overall relative risk of having at least one rejection episode in those who received fish oil was 0.91 (95% confidence interval 0.74 to 1.10) in four studies with a follow-up of 1 yr. A meta-analysis of eight RCT of graft survival found no significant benefit (relative risk 1.00, 95% confidence interval 0.96 to 1.05). The available data (mostly derived from older studies with important methodologic limitations) do not demonstrate a consistent, clinically important benefit of fish oil in kidney transplantation.

Clinical Trials as Topic↗
PubMed2005

Generalized low bone mass of girls with adolescent idiopathic scoliosis is related to inadequate calcium intake and weight bearing physical activity in peripubertal period.

Generalized low bone mass has been well documented in patients with adolescent idiopathic scoliosis (AIS). However, studies linking calcium-intake (CA), weight-bearing physical-activity (PA) and bone mass of AIS are lacking. We aimed to study the relationship between CA, PA and bone mass in AIS girls and compared to those of healthy non-AIS controls during the peripubertal period. Newly diagnosed AIS girls (n=596) aged 11-16 years with Cobb angle >/=10 degrees were recruited to compare with age-matched healthy girls (n=302) in a cross-sectional study. Anthropometric parameters, pubertal status, CA and PA were assessed. Areal bone mass of lumbar spine and femoral neck, and volumetric bone mass of distal radius and tibia were determined by dual-energy X-ray absorptiometry and peripheral quantitative computed tomography, respectively. The results showed that weight and body mass index (BMI) of AIS were lower than the controls (P<0.05). Corrected height and arm span of AIS were longer than those of controls from 13 years onwards (P<0.02). Median CA of AIS was <410 mg/day across the ages and did not differ from the controls (P=0.063). Median PA of AIS (1.6 h/day) was lower than the controls (1.8 h/day) (P=0.025). Bone mass of AIS was on average 6.5% lower than controls across the ages (P<0.05). CA and PA were significantly correlated with bone mass of AIS (P<0.04). Multivariate analysis showed that AIS in girls was associated with lower bone mass, and that both CA and PA were independent predictors of bone mass in AIS. In conclusion, AIS girls were found to have lower body weight and BMI, longer segmental lengths and generalized low bone mass. Inadequate calcium intake and weight-bearing physical activity were significantly associated with low bone mass in AIS girls during the peripubertal period. The importance of preventing generalized osteopenia in the control of AIS progression during the peripubertal period warrants further study.

Absorptiometry, Photon↗
PubMed2005

Long-term effectiveness of weight-loss interventions in adults with pre-diabetes: a review.

OBJECTIVE: To assess the effectiveness of weight-loss and weight-control interventions for adults with pre-diabetes (impaired fasting glucose and impaired glucose tolerance), an important risk factor for the development of type 2 diabetes. METHODS: Computerized searches were conducted of multiple electronic bibliographic databases up to August 2003. Randomized controlled trials in any language were selected that examined weight-loss or weight-control strategies using at least one dietary, physical activity, or behavioral intervention, and with a follow-up interval of a per thousand yen12 months. Effects were combined using a random effects model. RESULTS: Studies were identified, with a total of 5168 participants. Follow-up ranged from 1 to 10 years. Quantitative synthesis was limited by the heterogeneity of populations, settings, and interventions, and by the small number of studies that examined outcomes other than weight. Overall, compared to usual care, four studies with a follow-up of 1 year reduced weight by 2.8 kg (95% confidence interval [CI]=1.0-4.7) (3.3% of baseline body weight) and decreased body mass index by 1.4 kg/m(2) (CI=0.5-2.3). Weight loss at 2 years was 2.7 kg (CI=1.9-3.4) (two studies). Modest improvements were noted in the few studies that examined glycemic control, blood pressure, and lipid concentrations (p >0.05). The incidence of diabetes was significantly lower in the intervention groups versus the controls in three of five studies examining this outcome at 3 to 6 years follow-up. CONCLUSIONS: Overall, weight-loss strategies using dietary, physical activity, or behavioral interventions produced significant improvements in weight among persons with pre-diabetes, and a significant decrease in diabetes incidence. Further work is needed on the long-term effects of these interventions on morbidity and mortality and on how to implement these interventions in the community setting.

Adult↗
PubMed2005

Topical anesthetics for dermal instrumentation: a systematic review of randomized, controlled trials.

STUDY OBJECTIVE: We compare the analgesic efficacy of topical anesthetics for dermal instrumentation with conventional infiltrated local anesthesia and also compare topically available amide and ester agents with a eutectic mixture of local anesthetics (EMLA). METHODS: We conducted a systematic review of randomized, controlled trials. Relevant literature was identified through searches of MEDLINE, Cochrane Central Register of Controlled Trials, and the Excerpta Medica Database Drugs and Pharmacology. We limited the type of procedures to puncture of intact skin with a needle. The primary outcome was analgesic efficacy, reflected in the patient's self-report of pain intensity during dermal instrumentation. Where possible, quantitative methods were used to summarize the results. RESULTS: We identified 25 randomized controlled trials including 2,096 subjects. The results of the trials comparing the efficacy of EMLA with infiltrated local anesthetic were inconsistent. Qualitative analysis demonstrated comparable analgesic efficacy between liposome-encapsulated lidocaine and EMLA. The weighted mean difference in 100-mm visual analogue scale pain scores favored topical tetracaine over EMLA (-8.1 mm; 95% confidence interval -15.6 mm to -0.6 mm). Liposome-encapsulated tetracaine provided greater analgesia than EMLA according to the weighted mean difference in 100-mm visual analogue scale scores (-10.9 mm; 95% confidence interval -15.9 mm to -5.9 mm). CONCLUSION: EMLA may be an effective, noninvasive means of analgesia before dermal procedures. However, we identified 3 topical anesthetics that are at least as efficacious as EMLA: tetracaine, liposome-encapsulated tetracaine, and liposome-encapsulated lidocaine. Liposomal lidocaine is commercially available in the United States and offers a more rapid onset and less expensive alternative to EMLA.

Administration, Cutaneous↗
PubMed2005

Comparative efficacy and costs of various topical anesthetics for repair of dermal lacerations: a systematic review of randomized, controlled trials.

STUDY OBJECTIVES: To compare the efficacy of infiltrated local anesthesia with topical anesthesia for repair of dermal laceration, to analyze the efficacy of single or multicomponent topical anesthetics, and to identify topical formulations that are potentially less costly and equally efficacious as cocaine-containing topical anesthetics. DESIGN: Systematic review of randomized controlled trials. SETTING: University-affiliated hospital. PATIENTS: Pediatric and adult subjects. MEASUREMENTS AND MAIN RESULTS: Twenty-two trials that randomized more than 3000 patients were identified. The majority of studies demonstrated equivalent or superior analgesic efficacy for topical formulations compared with conventional intradermal infiltration. We found that cocaine is not a mandatory component of topical anesthesia. The literature discloses no significant difference in anesthetic efficacy between topical tetracaine-epinephrine-cocaine and each of the following 6 cocaine-free formulations: lidocaine-epinephrine-tetracaine, lidocaine-epinephrine, tetracaine-phenylephrine, tetracaine-lidocaine-phenylephrine, bupivicaine-norepinephrine, or prilocaine-phenylephrine. CONCLUSION: Topical anesthetics are an efficacious, noninvasive means of providing analgesia before suturing of dermal lacerations. The use of cocaine-containing topical anesthetics can no longer be justified in light of its high cost and potential adverse effects. We have summarized the evidence, mostly favorable, supporting the use of various non-cocaine-containing topical anesthetics.

Anesthetics, Local↗
PubMed2005

Does the evidence support the use of spinal and epidural anesthesia for surgery?

When spinal and epidural anesthesia were introduced into clinical practice, their primary use was as an alternative to general anesthesia. Later, largely as a result of the realization that opioids could be safely and effectively used to produce selective spinal analgesia, spinal and epidural (neuraxial) analgesia began to be used specifically for the treatment of perioperative pain. We present a systematic review of the literature on neuraxial anesthesia and analgesia, new meta-analyses that illustrate the powerful effect of improvements in perioperative safety in general on the ability of neuraxial techniques to make a difference, and a consideration of why a literature analysis does not provide clear answers.

Analgesia, Epidural↗
PubMed2005

In an empirical evaluation of the funnel plot, researchers could not visually identify publication bias.

BACKGROUND AND OBJECTIVE: Publication bias and related biases can lead to overly optimistic conclusions in systematic reviews. The funnel plot, which is frequently used to detect such biases, has not yet been subjected to empirical evaluation as a visual tool. We sought to determine whether researchers can correctly identify publication bias from visual inspection of funnel plots in typical-size systematic reviews. METHODS: A questionnaire with funnel plots containing 10 studies each (the median number in medical meta-analyses) was completed by 41 medical researchers, including clinical research fellows in a meta-analysis class, faculty in clinical care research, and experienced systematic reviewers. RESULTS: On average, participants correctly identified 52.5% (95% CI 50.6-54.4%) of the plots as being affected or unaffected by publication bias. The weighted mean percent correct, which adjusted for the fact that asymmetric plots are more likely to occur in the presence of publication bias, was also low (48.3 to 62.8%, depending on the presence or absence of publication bias and heterogeneous study effects). CONCLUSION: Researchers who assess for publication bias using the funnel plot may be misled by its shape. Authors and readers of systematic reviews need to be aware of the limitations of the funnel plot.

Humans↗
PubMed2005

A systematic review and meta-analysis of the impact of omega-3 fatty acids on selected arrhythmia outcomes in animal models.

Epidemiological studies and clinical trials report the beneficial effects of fish or fish oil consumption on cardiovascular disease outcomes including sudden death. We performed a systematic review of the literature on controlled animal studies that assessed the effects of omega-3 fatty acids on selected arrhythmia outcomes. On the basis of predetermined criteria, 27 relevant animal studies were identified; 23 of these were feeding studies, and 4 were infusion studies. Across species, fish oil, eicosapentaenoic acid, and/or docosahexaenoic acid appear to have beneficial effects on ventricular tachycardia (VT) and fibrillation (VF) in ischemia- but not reperfusion-induced arrhythmia models; no effect on the incidence of death and infarct size; and inconsistent results with regard to arrhythmia score, VF threshold, ventricular premature beats or length of time in normal sinus rhythm, compared to omega-6, monounsaturated, or saturated fatty acids, and no treatment controls. In a meta-analysis of 13 studies using rat models, fish oil but not alpha-linolenic acid supplementation showed a significant protective effect for ischemia- and reperfusion-induced arrhythmias by reducing the incidence of VT and VF. It is not known whether omega-3 fatty-acid supplementation has antiarrhythmic effects in other disease settings not related to ischemia.

Animals↗
PubMed2005

Systemic administration of local anesthetics to relieve neuropathic pain: a systematic review and meta-analysis.

We reviewed randomized controlled trials to determine the efficacy and safety of systemically administered local anesthetics compared with placebo or active drugs. Of 41 retrieved studies, 27 trials of diverse quality were included in the systematic review. Ten lidocaine and nine mexiletine trials had data suitable for meta-analysis (n = 706 patients total). Lidocaine (most commonly 5 mg/kg IV over 30-60 min) and mexiletine (median dose, 600 mg daily) were superior to placebo (weighted mean difference on a 0-100 mm pain intensity visual analog scale = -10.60; 95% confidence interval: -14.52 to -6.68; P < 0.00001) and equal to morphine, gabapentin, amitriptyline, and amantadine (weighted mean difference = -0.60; 95% confidence interval: -6.96 to 5.75) for neuropathic pain. The therapeutic benefit was more consistent for peripheral pain (trauma, diabetes) and central pain. The most common adverse effects of lidocaine and mexiletine were drowsiness, fatigue, nausea, and dizziness. The adverse event rate for systemically administered local anesthetics was more than for placebo but equivalent to morphine, amitriptyline, or gabapentin (odds ratio: 1.23; 95% confidence interval: 0.22 to 6.90). Lidocaine and mexiletine produced no major adverse events in controlled clinical trials, were superior to placebo to relieve neuropathic pain, and were as effective as other analgesics used for this condition.

Anesthetics, Local↗